ƒ ½ ¨ 7 Hë H Sae Mulli (The Korean Physical Society), Volume 48, Number 2, 2004¸ 2 Z 4, pp. 174∼177

 ƒ  ½ ¨ 7 Hë  H  Sae Mulli (The Korean Physical Society), Volume 48, Number 2, 2004¸   2 Z 4, pp. 174∼177

T

 ” Ò ÞŒ £ ?’ Ò ×(hetero-metal) 4H-÷ m ÇP  É b Ø  T © Ž(silicon carbide) } »² ŽW 



T ~ ¾© Ž8 ý  ¹ ÅM X ì Ä — ¤V R Ë

T „ ç ¡- ! H ^∗

„ 

· ¡ ¤ @ /† < Ɠ § ì ø ͕ ¸^ ‰õ † < Æl Õ ü t† < Æõ , „  Å Ò 561-756 (2003¸   12 Z 4 10{ 9  ~ à Î6 £ §)

\

# Qa % ¦(aerosol) ~ ½ ÓZ O Ü ¼– Ð ] j› ¸  ) a F K
” ¸{ 9  (gold nano-particles)[ þ t`  ¦ w  ³ o u(titanium) F K5 Å q \ 

| 9

# QV , “ É r(embedded) ½ ¨› ¸“   s 7 á xF K5 Å q z  ´o – B H  s × ¼ ® éà Ôv   s š ¸× ¼_  „  l & h “   : £ ¤$ í `  ¦ ƒ  ½ ¨

% i  . ‘ : r ƒ  ½ ¨\   6   x ) a „  l & h “   : £ ¤$ í 8 £ ¤& ñ ~ ½ ÓZ O “ É r „  À Ó-„  · ú šõ  H J r ‡  Û ¼-„  · ú š 8 £ ¤& ñ ~ ½ Ód ” `  ¦ s  6

 

x % i “ ¦, n-+ þ A_  ® éà Ôv   s š ¸× ¼[ þ t`  ¦ 4H-SiC l ó ø Í\  ] j Œ • # Œ 8 £ ¤& ñ `  ¦ % i  . 8 £ ¤& ñ “ É r l ï  r Ò  re  ¦, 7

£

¤ F K
” ¸{ 9   \ O   H w  ³ o u F K5 Å që ß –s  z  ´o – B H  s × ¼ 0 A\  7 £ x‚ à ̝ ) a ® éà Ôv   s š ¸× ¼ü < F K
” ¸ { 9

  embedded  ) a Ò  re  ¦ ¿ º t \  ¦ q “ § % i  . 8 £ ¤& ñ   õ , n-+ þ A ® éà Ôv   s š ¸× ¼(F K
” ¸{ 9  

embedded ) a)_   â Ä º 0.18 ∼ 0.25 eV ® éà Ôv   © œ# 4 s  l ï  r Ò  re  ¦ \  q K  ×  ¦ # Q[ þ U`  ¦ › ' a¹ 1 Ï % i  . › ' a¹ 1 ϝ ) a

®

éà Ôv   © œ# 4  ×  ¦ # Q[ þ U ‰ & ³ © œ“ É r F K
” ¸{ 9  _   Œ •“ É r ß ¼l ü < ¿ º s 7 á xF K5 Å q( w  ³ o u õ  F K)ç ß –_   H ® éà Ôv   © œ# 4  Z

 } s  – Ð “  ô  Ç „  l  © œs  7 £ x @ / €  " f Ï ã ÎF G& h Ü ¼– Ð ® éà Ôl   © œ# 4 s  ×  ¦ # QŽ  H    H dipole layer approach – Ð [ O

" î ½ + É Ã º e ” % 3  . Æ Ò– Ð Z  } >  • ¸i ç  ) a p

⁺

\ x 8 £ x \ " f_  TLM(transmission line method) J × ¼\  ¦ s  6

 

x # Œ l ï  r Ò  re  ¦( w  ³ o u š ¸b ” ] X 8 ú ¤) õ  F K
” ¸{ 9   embedded  ) a s 7 á xF K5 Å q š ¸b ” ] X 8 ú ¤`  ¦ q “ §ô  Ç    õ

, F K
” ¸{ 9   ” > r F    H š ¸b ” ] X 8 ú ¤ s  8 ú x $ † ½ Ó ° ú כs  ± ú 6 £ §`  ¦ S X ‰ “   % i  .

PACS numbers: 71.20.Nr, 73.40.Ei

Keywords: z  ´o – B H  s à Ô, ® éà Ôv   s š ¸× ¼, F K
” ¸{ 9  , s 7 á xF K5 Å q, ® éà Ôv   © œ# 4  Z  } s , 4H-SiC

I. " e  ] Ø

V ,

“ É r { ç ß –   ì ø ͕ ¸^ ‰ ×  æ 
“   z  ´o – B H  s × ¼(silicon carbide)  H “ ¦Ä »_  Ä ºÃ ºô  Ç : £ ¤$ í Ü ¼– Ð “   # Œ “ ¦“ : r, “ ¦Ø  ¦§ 4 ,

“

¦5 Å q ™ è \  6 £ x6   x s  0 p xô  Ç ì ø ͕ ¸^ ‰– Ð y Œ •F  g`  ¦ ~ à Γ ¦ e ”   [1]. s  Qô  Ç : £ ¤$ í “ É r l ” > r_  z  ´o – B H s 
 > Ø Ô ³ o u ì ø ͕ ¸^ ‰

˜

Ð   8 Z  }“ É r „  l  © œõ  V , “ É r { ç ß –  Ü ¼– Ð “   # Œ “ ¦“ : r x 9 

“

¦Ø  ¦§ 4 6   x ® éà Ôv   s š ¸× ¼ 1 p x \  & h 6   x s  0 p x  . F K5 Å q- ì

ø ͕ ¸^ ‰ ™ è _  6 £ x6   x \  e ” # Q" f ×  æ כ ¹ô  Ç כ ¹™ è  H ® éà Ôv   © œ

#

4  Z  } s (Schottky barrier height, SBH)s  . 6 £ x6   x # 3 0 A\ 



 " f, Z  }“ É r SBH  כ ¹½ ¨÷ &l • ¸ “ ¦ ± ú “ É r SBH  כ ¹½ ¨

÷

&l • ¸ ô  Ç .  € ª œô  Ç z  ´o – B H  s × ¼(3C-SiC, 4H-SiC, 6H-SiC) l ó ø Í`  ¦ s 6   xô  Ç ® éà Ôv   s š ¸× ¼ ] j Œ • x 9  : £ ¤$ í

\

 › ' aº   ) a ´ ú §“ É r ƒ  ½ ¨  7 Hë  H[ þ t s  Ø  ¦ó ø Ís  ÷ &% 3 Ü ¼ 9 [2, 3], Itoh 1 p x [4] õ  Lee 1 p x [5]“ É r ® éà Ôv   © œ# 4 _  Z  } s   H F K5 Å q_  { 9

 † < Êà º(work function)\  q Y V # Œ _ ” > r† < Ê`  ¦ z  ´+ « >& h Ü ¼

–

Ð ˜ Ð# Œº ¡ § Ü ¼– Ð+ ‹ Fermi-level_  unpinning ‰ & ³ © œ`  ¦ 7 £ x" î 

%

i  . s   H s p  · ú ˜ 9”   F K5 Å q`  ¦ ‚  × þ ˜ # Œ z  ´o – B H  s 

∗

E-mail: sk [email protected]

×

¼ ì ø ͕ ¸^ ‰\  ] X ½ + Ë`  ¦ r v €  , ‚  + þ A& h “   › ' a > d ” \  _ K " f,

®

éà Ôv   © œ# 4  Z  } s (SBH)\  ¦ Ä »Æ ÒK  è ­ q à º e ”  . ® éà Ôv    s

š ¸× ¼ü <  8Ô  ¦ # Q ‰ & ³F  V , “ É r { ç ß –   ì ø ͕ ¸^ ‰ “ ¦Ø  ¦§ 4  ™ è



\  ¦ 6 £ x6   x   H X < e ” # Q" f   a Ë >[  t ×  æ 
  H ± ú “ É r š ¸b ” ] X  8

ú

¤ $ † ½ Ó° ú כ(ohmic contact resistivity)s   [3]. ± ú “ É r š ¸b ”  ] X

8 ú ¤ ° ú כ`  ¦ % 3 l  0 AK " f  H F K5 Å q õ  ] X 8 ú ¤ s  s À Ò# Qt   H ì ø Í

•

¸^ ‰\  S X ‰í ß – x 9  s “ : r Å Ò{ 9  ~ ½ ÓZ O  1 p x`  ¦ : Ÿ x # Œ ´ ú §“ É r H o 

#

Q(carriers)[ þ t`  ¦ Å Ò{ 9    H ~ ½ ÓZ O õ  & h ] X ô  Ç F K5 Å q`  ¦ ‚  × þ ˜ 

#

Œ ± ú “ É r SBH\  ¦ Ä »t    H ~ ½ ÓZ O s  e ”   [6].

‘

: r  7 Hë  H“ É r l ” > r_  ® éà Ôv   s š ¸× ¼_  ] j Œ • ~ ½ ÓZ O õ   H

²

ú ˜o , \ # Qa % ¦(aerosol) ~ ½ ÓZ O Ü ¼– Ð ] j› ¸  ) a F K
” ¸{ 9  (gold nano-particles)[ þ t`  ¦ s 6   x # Œ w  ³ o u(titanium) F K5 Å q \ 

| 9

# QV , “ É r(embedded) ½ ¨› ¸_  s 7 á xF K5 Å q z  ´o – B H  s × ¼

®

éà Ôv   s š ¸× ¼\  ¦ ] j Œ • x 9  : £ ¤$ í ì  r$ 3 \  › ' aô  Ç ? /6   x s  .

¢

¸ô  Ç, s   7 Hë  H“ É r  € ª œô  Ç z  ´o – B H  s × ¼ l ó ø Í\  F K


”

¸{ 9  \  ¦ | 9 # QV , “ É r w  ³ o u ® éà Ôv   s š ¸× ¼\  ¦ ] j Œ • # Œ F

K
” ¸{ 9  [ þ t \  % i ½ + É\  › ' a K  œ í& h `  ¦ ¿ º% 3  . ¢ ¸ô  Ç, Æ Ò

&

h Ü ¼– Ð enhanced  ) a „  l  © œ_  % ò † ¾ Ó`  ¦ S X ‰ “   l  0 AK  ç ß –

 

s  { 9 & ñ ô  Ç F K5 Å q õ  F K5 Å q  s _  8 ú x $ † ½ Ó° ú כ(\ x 8 £ x $ † ½ Ó + ] X 8 ú ¤ $ † ½ Ó)`  ¦ 8 £ ¤& ñ % i  .

-174-

 ƒ  ½ ¨ 7 Hë  H  s 7 á xF K5 Å q(hetero-metal) 4H-z  ´o – B H  s × ¼(silicon carbide) ® éà Ôv   s š ¸× ¼_  „  l & h  : £ ¤$ í – s  © œ Ý ¶ -175-

Fig. 1. Schematic view of Ti Schottky diode with em- bedded Au nano-particles on 4H-SiC.

II. ÷ m Ç ] M ö

z 

´o – B H  s × ¼  H stacking order  # Qb  G>  ÷ &Ö ¼
\ 



 " f, # Œ Q t _  polytypeÜ ¼– Ð ½ ¨Z > s   ) a  (2H-, 4H- , Õ ªo “ ¦ 6H-SiC). Õ ª ×  æ 4H-SiC J ?s (   H  s ß ¼– Ð   s

á Ô x 9 • ¸  © œ  Œ •Ü ¼Ù ¼– Ð ‰ & ³F  # 3 6   x Ü ¼– Ð  6   x ÷ &“ ¦ e ” 



 [3]. ‘ : r z  ´+ « >\   6   x ) a Ò  re  ¦“ É r CREE \ " f ½ ¨{ 9 ô  Ç  כ Ü ¼

–

Ð 4H-SiC(≈10

¹⁸

cm

⁻³

) l ó ø Í 0 A\   s š ¸× ¼ : £ ¤$ í `  ¦ 0 A K

 Z > >  • ¸i ç s   ) a n-+ þ A 4 µm ¿ ºa _  \ x 8 £ x(epitaxial layer, ≈5 × 10

⁻¹⁵

cm

⁻³

) s  7 £ x‚ à Ìs   ) a J ?s ( \  ¦  6   x 

%

i  . Æ Ò– Ð $ † ½ Ó 8 £ ¤& ñ `  ¦ 0 AK  Z  } >  • ¸i ç s   ) a p

⁺

4H- SiC \ x 8 £ x(1 µm)`  ¦  6   x % i   [7]. Fig. 1“ É r F K
” ¸{ 9 



[ þ t s  embedded w  ³ o u ® éà Ôv   s š ¸× ¼ @ /| Ä Ì& h “   ½ ¨

›

¸• ¸\  ¦ ˜ Ð# Œï  r  . €  $  ï  r q   ) a J ?s (   H 2 é ß –>  ß ¼ 2 ;_ ç

`

 ¦ z  ´r ô  Ç . s   H J ?s ( \  · ¡ ­ # Qe ”   H Ä »l  Ô  ¦í  HÓ ü t õ  ³ ð

€ 

`  ¦ ß ¼ 2 ;_ ç l  0 AK  z  ´r   ) a  . ' Í   P : é ß –>   H H

2

SO

4

: H

2

O

2

\  ¦ 2.5 : 1_  q Ö  ¦ – Ð [ O # Q" f 5ì  rç ß – ß ¼ 2 ;_ ç ô  ÇÊ ê   r

 6 \ šl \  IMEC ƒ  ½ ¨™ è [8]\ " f > hµ 1 Ïô  Ç Ñ ü t P : ß ¼ 2 ;_ ç ~ ½ Ó Z O

“   6   xÓ  o(H

₂

O : CH

3

CH(OH) CH

3

: HF=100 : 3 : 1) \  ß

¼ 2 ;_ ç `  ¦ z  ´r ô  Ç . F K
” ¸{ 9   ß ¼l  › ¸] X s  0 p xô  Ç ~ ½ Ó Z O

“   \ # Qa % ¦(aerosol) ~ ½ ÓZ O Ü ¼– Ð { 9   t 2 £ § s  20 nms  9 x 9

• ¸ 90 µm

⁻²

“   F K
” ¸{ 9  [ þ t`  ¦ z  ´o – B H  s × ¼ l  ó

ø Í 0 A\  7 £ x‚ à Ì`  ¦ r †   .  [ jô  Ç z  ´+ « > ~ ½ ÓZ O “ É r ‚ à Г ¦ ë  H‰  ³`  ¦

‚

à Л ¸  ê ø Í  [9]. F K
” ¸{ 9  [ þ t s  7 £ x‚ à ̝ ) a Ê ê   É r F K5 Å q“   w

 ³ o u(Ti)`  ¦ F K
” ¸{ 9   0 A\  Fig. 1õ  ° ú  s  thermal evaporation ~ ½ ÓZ O Ü ¼– Ð 7 £ x‚ à Ì`  ¦ r †   . þ j7 á x& h Ü ¼– Ð z  ´o 

–

B H  s × ¼ ® éà Ôv   s š ¸× ¼  H photo-lithography ~ ½ ÓZ O 

`

 ¦ : Ÿ x # Œ ] j Œ •s  ¢ - a « Ñ  ) a  . q “ §& h “   z  ´+ « >`  ¦ 0 A # Œ F K

” ¸{ 9   \ O   H w  ³ o u ® éà Ôv   s š ¸× ¼(l ï  r Ò  re  ¦ – Ð

"

î " î )[ þ t`  ¦ ° ú  “ É r / B N& ñ Ü ¼– Ð 1 l x r \  ] j Œ • % i  . # Œl " f s  7

á

x F K5 Å q Ü ¼– Ð F K õ  w  ³ o u`  ¦ ‚  × þ ˜ô  Ç  © œ  H s Ä »  H s  [

þ

t F K5 Å q[ þ t s  n-+ þ A 4H-SiC\  @ / # Œ  © œ  H ® éà Ôv   © œ

Fig. 2. Schttky barrier height of Ti Schottky diodes and Ti Schottky contacts with embedded Au nano-particles to 4H-SiC as a function of measurement temperature us- ing I-V measurements.

#

4  Z  } s (SBH)\  ¦ ° ú “ ¦ e ” l  M :ë  H s  . 7 £ ¤, n-+ þ A 4H-SiC

“

   â Ä º  H 0.63 eV s \  ¦ ° ú   H   [3]. ] j Œ •s  ¢ - a « Ñ  ) a Ò  r e

 ¦[ þ t“ É r 10 %H

2

/Ar_  ì  r0 Al ü < 350 ∼ 550

^◦

C \ " f 60œ í ç

ß – RTA(rapid thermal annealing) ô  Ç . „  l & h “   8 £ ¤& ñ “ É r

„ 

À Ó-„  · ú š(I-V)õ  H J r ‡  Û ¼-„  · ú š(C-V) 8 £ ¤& ñ `  ¦ : Ÿ x # Œ

®

éà Ôv   s š ¸× ¼_  : £ ¤$ í `  ¦   & ñ t # QŠҍ  H SBH ü < ideality factor\  ¦ Ä »Æ ÒK  l ï  r Ò  re  ¦ õ  q “ §  9, Æ Ò– Ð $ † ½ Ó ° ú כ 8

£

¤& ñ `  ¦ 0 AK  100 × 100 µm

²

_  TLM(transmission line method) J ‡  `  ¦ ] j Œ • # Œ I-V\  ¦ : Ÿ x K  ¿ º > h_  J ‡    s  _

 8 ú x $ † ½ Ó ° ú כ`  ¦ 8 £ ¤& ñ ô  Ç .

Fig. 3. Calculated electric field distribution for n-type

4H-SiC as a function of the radius of the circular patch

and depth from the surface. The inset shows a schematic

diagram of a high barrier circular patch (Au) surrounded

by low barrier metals (Ti) on SiC.

-176- ô  Dz D GÓ ü t o † < Æ rt  “D hÓ ü t o ”, Volume 48, Number 2, 2004¸   2 Z 4

Table 1. Summary of the SBH and ideality factor as a function of the measurement temperature for particle- free control Ti contacts and Ti Schottky diodes with Au nano-particles embedded on n-4H-SiC using I-V and C-V measurements.

n- Temp 75 or 125 or

4H-SiC SMPL

· 25

50

^a

100

^b

φ

B

0.93 0.93 0.93 Nano η 1.04 1.03 1.03 IV

^a

φ

B

1.12 1.11 1.11 Ti η 1.03 1.03 1.05 Nano φ

B

0.73 0.75 0.69 CV

^b

Ti φ

B

0.93 0.98 0.99 IV

^a

 â Ä º  H 25, 50, 100

^◦

C \ " f 8 £ ¤& ñ

CV

^b

 â Ä º  H 25, 75, 125

^◦

C \ " f 8 £ ¤& ñ

III. + s ÇÊ Ý õ m Í À X Ø8 ý

Thermionic-emission s  : r \    H   # Œ I-V 8 £ ¤& ñ   õ 

–

РÒ'  n-+ þ Aõ  p-+ þ A\  @ /ô  Ç SBH ° ú כ`  ¦ Ä »• ¸K  è ­ q à º e ”

 . Table 1“ É r F K
” ¸{ 9   embedded  ) a s 7 á xF K5 Å q

®

éà Ôv (Nano)  s š ¸× ¼ü < w  ³ o u ® éà Ôv   s š ¸× ¼_  SBH(φ) ü < ideality factor(η) ° ú כ`  ¦ & ñ o  % i  . ¢ ¸ô  Ç n- + þ

A x 9  p-+ þ A_    õ \  ¦ ½ ¨ì  r % i  . ³ ð 1\ " f ˜ Ѝ  H  ü < ° ú   s

 SBH  H F K
” ¸{ 9   embedded  ) a  â Ä º “ : r • ¸ # 3 0 A 25 ∼ 125

^◦

C  s \ " f 0.93 eV% i Ü ¼ 9, l ï  r Ò  re  ¦_   â Ä

º  H 1.11 ± 0.01 eVe ” `  ¦ · ú ˜ à º e ”  . s   H F K
” ¸{ 9  

 embedded  ) a ® éà Ôv   s š ¸× ¼_   â Ä º_  SBH 0.18 eV ×  ¦ # Q[ þ t% 3 6 £ §`  ¦ · ú ˜ à º e ”  . s   H C-V 8 £ ¤& ñ   õ – РÒ'  F

  S X ‰ “   H † d`  ¦ · ú ˜ à º e ”  . (0.25 eV ×  ¦ # Q[ þ U). Fig. 2  H



€ ª œô  Ç “ : r • ¸ # 3 0 A\ " f_  F K
” ¸{ 9   embedded  ) a ® é à

Ôv   s š ¸× ¼ü < l ï  r Ò  re  ¦“   w  ³ o u ® éà Ôv   s š ¸× ¼ _

 SBH\  ¦ q “ § % i  . Fig. 2\ " f ˜ Ѝ  H   ü < ° ú  s  S X ‰ z  ´

>  F K
” ¸{ 9   embedded  ) a Ò  re  ¦_  SBH  Œ •6 £ §`  ¦ S X

‰ “  ½ + É Ã º e ”  . ¢ ¸ô  Ç, ¿ º Ò  re  ¦ — ¸¿ º “ : r • ¸\  @ / # Œ î ß –

&

ñ & h “   ° ú כ[ þ t`  ¦ ˜ Ð# Œï  r  . 0 A\ " f embedded  ) a F K
” ¸{ 9 



[ þ t – Ð “  ô  Ç SBH ×  ¦ # Q[ þ U ‰ & ³ © œ(SBH lowering)`  ¦ ½ ©" î  l

 0 AK  Tung_  dipole layer ] X   H ~ ½ ÓZ O `  ¦ • ¸{ 9 ô  Ç  [10].

s

 כ Ü ¼– РÒ'  F K5 Å q õ  ì ø ͕ ¸^ ‰ ] X 8 ú ¤ ÷ &# Qe ” `  ¦ M :_  Ÿ íJ $ ™ [ >

(potential) ì  r Ÿ í  H  6 £ § d ”  (1)õ  ° ú   .

V (0, 0, z) = V

bi

 1 − z

W



²

+ V

a

+ V

a

− ∆φ

T i−Au



1 − z sqrt(z

²

+ R

²₀

)

 (1)

#

Œl " f R

0

  H F K
” ¸{ 9  _  ì ø Ít 2 £ § s “ ¦(≈10 nm),

∆φ

_{T i−Au}

( ≈0.63 eV)“ É r F K õ  w  ³ o u_  SBH_  s s  .

d ”

 (1)`  ¦ p ì  r €   Fig. 3\  ˜ Ѝ  H  ü < ° ú  s  F K
” ¸{ 9 

Fig. 4. The total resistance for Ti ohmic contacts and Ti ohmic contacts with Au nano-particles embedded on 4H-SiC as a function of annealing temperature.



_  ì ø Ít 2 £ § õ  U  ·s (z)\    É r „  l  © œ_  ì  r Ÿ í\  ¦ ½ ¨½ + É Ã º e ”

 . Fig. 3\ " fü < ° ú  s  F K
” ¸{ 9    Œ •Ü ¼€    Œ •`  ¦ à º 2

Ÿ

¤ „  l  © œs  7 £ x † < Ê`  ¦ · ú ˜ à º e ”  . \ # Qa % ¦ ~ ½ ÓZ O Ü ¼– Ð ] j

›

¸  ) a F K
” ¸{ 9  _  ì ø Ít 2 £ § s  10 nms Ù ¼– Ð s  — ¸4 S q– Ð

"

f > í ß –s   ) a „  l  © œ“ É r 0.068 × 10

⁷

V/cm s  . s  ß ¼l  _

 „  l  © œÜ ¼– Ð “  ô  Ç SBH lowering(image force lowering), 7

£ ¤ ∆φ = (qE/4π

s

)

^1/2

s Ù ¼– Ð > í ß –d ” Ü ¼– РÒ'  0.1 eV_  SBH lowering ´ òõ \  ¦ % 3 `  ¦ à º e ” % 3  . s   H · ú ¡\ " f z  ´+ « >

&

h Ü ¼– Ð % 3 “ É r SBH(0.18 eV) \    H] X    H à ºu e ” `  ¦ · ú ˜ à º e ”

 .   " f, 8 £ ¤& ñ  ) a SBH ×  ¦ # Q[ þ U ‰ & ³ © œ“ É r  Œ •“ É r ß ¼l _  F K

” ¸{ 9  (t 2 £ § 20 nm) ü < F K õ  w  ³ o u_  SBH \ " f l 

“

 ô  Ç Z  }“ É r „  l  © œ`  ¦ : Ÿ x K " f SBH  ×  ¦ # Q[ þ U Ü ¼– Ð [ O " î s 

0 p x  . Æ Ò& h Ü ¼– Ð n  s Û ¼ r Ó ý t Y Us ' “   2D Atlas

™

èá Ôà ÔJ ?# Q\  ¦ s 6   x # Œ r Ó ý t Y Us ‚  `  ¦ z  ´r ô  Ç   õ , „   l

 © œs  F K5 Å q[ þ t(Au, Ti) õ  ì ø ͕ ¸^ ‰_   â >  €  \ " f Z  }6 £ §`  ¦ S X

‰ “  ½ + É Ã º e ” % 3  . · ú ¡\ " f µ 1 ß) €”   F K
” ¸{ 9  – Ð “  K  µ 1 Ï Ò q

t ) a Z  }“ É r „  l  © œs  tunneling current\  # Qb  G>  % ò † ¾ Ó`  ¦ p

u   H t \  ¦ S X ‰ “   l  0 AK  TLM J ‡  `  ¦ ] j Œ • # Œ ¿ º > h _  J ‡    s _  8 ú x $ † ½ Ó° ú כ`  ¦ 8 £ ¤& ñ % i  . Fig. 4  H \ P % ƒ o

 “ : r • ¸\    É r 8 ú x $ † ½ Ó° ú כ_     o\  ¦ ˜ Ð# Œï  r  . 650

^◦

C s 



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Electrical Characterization of Hetero-Metal (Embedded Au Nano-Particles and

Titanium Metal) Schottky Diodes on 4H-Silicon Carbide

Sang-Kwon Lee

^∗

Department of Semiconductor Science and Technology, Chonbuk National University, Chonju 561-756

(Received 10 December 2003)

We investigated the electrical characterization of Ti Schottky diodes with embedded Au nano- particles on n-type 4H-silicon carbide 4-H(SiC). From our measurements (I-V and C-V), we observed that hetero-metal Ti Schottky diodes (embedded Au nano-particles and Ti) had 0.18 ∼ 0.25 eV lower barrier heights than those of particle-free Ti Schottky diodes on n-type 4H-SiC. These phenomena suggest that SBH lowering is caused by an enhanced electric field due to the small size of the Au nano-particles and by the large SBH difference between Au and Ti. We also tested these contact schemes on highly doped p

⁺

SiC material in order to study ohmic contacts using linear TLM measurements. The results indicated that the ohmic contact with embedded Au nano-particles showed a lower total resistance compared to the particle-free samples.

PACS numbers: 71.20.Nr, 73.40.Ei

Keywords: Silicon carbide, Schottky diodes, Au nano-particles, Hetero-metal, SBH, 4H-SiC

∗

E-mail: sk [email protected]